Influence of the growth parameters on the dielectric loss at microwave frequency of freestanding diamond thick films

The dielectric loss tangent (tan δ) at microwave frequency of freestanding diamond thick films, determined by resonant methods was studied. Deposition temperature and methane concentration were systematically varied in order to establish deposition processes that provide low loss materials for optical applications. The correlation was observed between the growth parameters and the dielectric loss at microwave frequency. The dielectric loss at microwave frequency of diamond films increases with an increase of the deposition temperature, while decreases with increasing methane concentration. A quality characterization of the diamond films by Raman spectroscopy, scanning electron microscopy and X-ray diffraction were also reported.